Device for inserting wire coils in tapped holes



N.` EvANs `2,316,231 ,DEVICE YPQR 4INSER'LINGWIREc'o1Ls` IN TAPPED HOLES April 13', `1943.

vFiled V.mma 16. i942 Kv NWN hm'.

Q@ Sy 4.

`Piumini Apr. 13, 194s p y i 2.316.231 n nnvrc'a ron msna'rrNG wmnc'orLs 1N 1 j y Terran noms i Neil Evans, Montclair, N. I., assignorltoAircraft I Screw Products Company, Inc., ALong' Island i City, N. 1.a corporation of New York` Application Jane 1s, 4194.2, Serin No: 447,336`

9 Claims. (Cl. iq-l) t v invention relatesrtol `amethod and a tool l `for insertinga wire coil ina` tapped ;.ho1e of a boss or similar part. Coil insertsfof the kind herev in consideration are `used for various pur- 1 poses. for instance in` order to provide` a tapped `threadin amember of, relatively soft material,

such as wood, aluminum, artiiclal matter, etc.,

. with a hardlining resistant to thedeteriorating` n `eilect of a bolt repeatedly screwed in and outof` l the thread `convoluticuis. .In' suchapplicationsfof wire coil inserts. it is'usually required that the inengage` thetapped threadgroove lunder radial tension, and,.thus, to set up considerablefrlction @between the coil convolutions4 and the anks of l the tapped groove.` Thefrictionprevents or at H L least counteracts forces tending to shift the insert i relatively `to `the member into which it is in-` t The insertion ofsuch oversized coil in `a tapped Y i l hole requires contraction of thecoil before itis l `ilnallyin its inserted position. Hitherto. the contractionhas been accomplished during and by 1 2i screwing the coil into` the thread ofsmaller the construction and arrangement of the parts'of "the tool being such that thecoil can be inserted into the tapped holewhile beingl held in a contracted state. and that it will be released to spring into ilrmengagement with the tapped threading when substantially its'whole length is inserted.

" sert wire is originally coiledloversized asto its.. `diameter in otderj to cause the inserted coil to zio diameter. In other words, lthermeniber into which n l l fthecoil was to beinserted, acted, in a sense, `as s the tool or at least part oi' al tool for. the con- Itraction of the coil. Ihismethodisobjectionable mainly fortwo reasons.` On `the one hand,`fre,

znquently the first convolution of the f tapped threading is destroyed or at least injured when `:the oversized insertwis forced intoit. On the other` hand, the more theinse'rt is advanced, the

` greater `becomes the `friction which resists the `inserting operation. .t

y Further objects and details ofthe invention will be apparent fromthe description given hereinafter andthe accompanying drawing illustrating an embodiment thereof by way of example. In thedrawing, n y" .w

Figs. 1 and 2 are side Velevation and front view respectively of an insert of thekind to which the invention relates. V i i easing insertto'be' contracted. l

' Fig.` `4 Lis another side-elevation of the same tool in '-a' position i`n` whichthe insert is contracted.` y l Y Fig..5 vis afront view of the tool. Fig;

the tool; v

Flg.'1 is a longitudinal cross-section of a modijiication ofanother portionof thetool."

.Referring `now to the drawing, Figs. 1 and 2 show an example of an insert of the kind here in "consideration 'Ifheillustrated coil III is wound of `a wireof suitablyselected. springy material. It

has a diamond-shaped cross-section. fHowever,`

it` isto be understood that thewire may be of any other v. suitable Vcross-section, e. g. round.`

` square orl pear-shaped. The outer diameter of The invention `aims,..therefo`re to provide a J `method and means wherebya wire coil can be in- `serted ina tapped `hole withoutlnjury to the` l threading and without undue frictionidurlng the? z l insertion. i

` 'I'he invention" consists in that theoversized `wire coil is first contracted to Aan outer diameter l smaller than the corresponding diameter of the `tappedhole for which the coil is destined. Then,`

the coil `is inserted into thetappedvhole While l beingheld thus contracted,` andiinally is released y tospring into iirmengagement with the tapped L "threading when in the desired/relative position 1.thereto. l

The invention furthervconsists in a tool coml `prising meansto hold oneend` of a coil,` and to yoontract the coil progressively'by a relative movej ment of theholdlng means and of another means 1in engagement with another "portion of the coilf,

Ynor a tang such as i3.

Now, in `order to insert into a tapped hole, a coilyhaving a, diameter larger than the corre` :this coil is larger than the corresponding diameter `of thetapped holefor'whlch it is destined; In

` order to facilitate the insertion the first vcon-` yvolution Il or a portion thereof may have an outer diameter slightly smaIIenthan the remainderflZ of the' coil. and in order to provide `for agrip by an inserting tool,'the front end of the coil maybe bent inward so as'to form a tang' y I3.` In other types ,l of inserts "there may be neither afront convolution with smaller diameter sponding diameter of the tapped hole, it is necessary to reduce the coil diameter. According'to` the present invention this is done by gripping the one end, preferably the tang, on the onehand. andalso `gripping thev other end of the coil. on the other hand,- and turningthe two gripped ends with respect to each other in such a sense as to increase the 'total `angle of the convolutions,

`theereby to `contract .theooiLv "Ihen, the coil in g; ,'i is a side-elevation ofa' `toolaccordlng` to my invention in `a positlonpreparatory to en- 6 is a sideview ofa modifiedportion of Y k state.

itsl contracted statewill be substantially comn lpletely inserted into the hole and, finally, released Y, so as to spring into close contact-with the flanks and-or bottom -of the tapped thread groove.

If the coil is so contracted that its outer diameter is smallerthantheiminimum diameter of the threadk convolutions ofl'the tapped ho1e.the

coil maybe inserted by shifting it axially in position. However, this is not alwaysv advisable,

' particularly if there arelands between thethread convolutions of the hole, lbecause: it may happen that the coil convolutions when released spring to bear against such lands rather than into the grooves of the thread. For this reason it is preferred to contract the coil diameter to a size only slightly smaller than'the correspondingdiameter equal to that of the coil I in its original, i. le.,

non-contracted state. Hence, the diameter at 26 is largerand the diameter of the threading 23 is smaller than the corresponding diameter of i the tapped hole which is to beflined by the coil.

Portion is deeply recessed at 21 and of such a length that a coil I0 can be inserted from the side between the'bushing I9 and end portion 22. Means may be provided in order to prevent an undesired relative movement between the rod I4 and part I8. In the illustrated embodiment, such `means consists of a set screw 28 inserted' into a radial tapped hole 29 of the bushing I9, and a Y liber disk 3l) is positioned between the 4set screw of the tapped lthread. Such a coil' can be easily screwed into position, practically without friction, owing to the clearance between'the corresponding diameters. l

The method hereinbefore described-and p ar-V ticularly the operation yof contracting the coil I may be modified inthat the fone endl of the coil is gripped as hereinbefore described, then hold l istaken of a portion of the coil close to said end.

This hold is progressivelyshifted towards the other endk while a forceis simultaneously applied between the gripped Aend and the holdin such a sense as to increase the total angle of convolution between the grippedend'and the hold. When the coiliis completely contracted it.' isinserted and t, Vreleased as in the rst described method. It is also possible, VaccordingA to the invention' first to contract a portion of the coil in the manner herelinbefore described, then to start linsertingthe contracted'portion between the gripped end and the hold, and tor-ontinue to-insert while the hold is'shifted towardssaidotherend. However, it is essential in any 'eventI that only a pre-contracted portion of the coil is insertedand that the coil stantially-the entire contracted coil has been in- I' serted.

and the rodv I4 whereby a desired braking effect v'can be obtained. vAn extraneous member 3l with a hole 32 tapped at 3,3 is indicated in Fig. 4.

lThe tool may be applied inthe followingmanner:v The rod I4 is retracted in bushing I9 so that its forward end I5 does not obstruct the recess -21 as shown vin Fig. 3. Then, a coil I-is inserted in to the recess with its tang-provided end towards the part 22 of the member I8. As y the diameter at 26 is equal to the outer diam- -eter of the main rcoil portionin its'original state, the coil abutting against the inner face of the portion 25 will be in a position where it is substantially co-axial with `the rod I4. The rod end I5, is, then, .pushed forward, i. e., towards the left hand side in the drawing, and through the coil, if necessary while turning it relatively to the latter, so that Vthe end of the rod catchesl y* the tang I3 in its slot I6 vand shifts the coil is'rreleased to springinto position only after sub-y 'd The novel toolillustratedin`Figs.f3 to 5 is use--r ful to apply the method according to the invention. It comprises a cylindrical rod I4 of adiameter substantially equal yto the inner diameter, after contraction of a coil for which the tool is l f destined. The front end I5 of the'y rod is tapered and'provided witha slotl Iii/so shaped that it can receive the tang I3 of a coil I0. The other end issuitably shapedat II for the attachment of extraneous means (not shown),'eithe r ymanually ragainst that face of the portion 22 which isopposite the bushing I 9; Thereafter, the rod I4 'is turned relatively to the bushing I9 whereby the front convolution I I of the coil will be caused to enter thethreading 23 of the portion 22. The recess 24', yif prqvided in portion 22, permits observation of the correct entrance of the coil into the threading 23. The relative rotation of the two members of the tool is continued with the` -result that the coil is progressively screwed' through the threading 23 so as to project'from the front end of the member I8 as clearly shown -in Fig. 4, thereby, the diameter of the main coil y., portion I2 will be reduced to that 'of the thready ing which is according to the desired dimension of the coil in its contracted state as mentioned hereinbefore. During this step of operation, the,N

n rod acts as a mandrel, its diameter being subor mechanically operated, whereby the rod may be shifted longitudinally and/or turned or held against turning. Anothermember I8 of the tool comprises a cylindrical portion I9 constituting a bushing with a longitudinal bore 20 in which the rody I4 has a 'sliding fit." VThe outer surface of the bushing is so shaped, for instance by knurling as indicated at 2|,l that `it' can be safely held and that a torque-can be applied between the bushing and the rod I4.r 1 The frontend 22 of the member I8 is cylindrical and may have the same outer v vdiameter as the/,bushing I9..y It is interio'rly threaded at 23'. The form,l vpitchand diameter of the threading corresponds to the shape the coil I0vis intended to have when in its contracted .l The. lengthr of the end 22 is vpreferably Y stantially equal to the inner diameter of the contracted c oil. The relative rotation of the two tool members I4 and I8is discontinued when there `is still a short length'of the trailingend of the coil in engagement 'with the threading. I have found that approximately half a convolution is sufficient to hold the rear end of the coil in such a relation to the front end that the coil remains contracted on'the rod I4. The resilient Y force set up by contracting the coil tends to turn vthe tool members in the direction opposite to that in which the members were turned during the contraction. Suchl movement, however, is prevented by the braking action of the fiber plate 30 pressed against rod I4 bythe properly adjusted set screw 28. "Thus, vthe coil is first contracted and then held by the tool in its contracted state. Now, the tool end` I5 with thev contracted coil on rod I4 can be inserted in the hole 32 of a member such as l3l. This can be accomplishedv by turning the rod I4 so as to screw v the contractile threading 33: It will be noticed that during the insertion the coil stays contracted owing to the braking means, i. e., set screw 28 d t i 2,316,231 pressing fiber disc` against rod I4. When the insertion of the coil is so far accomplished that the front face of the portion 22bears against the face 34 of the part 3|, member I8 is held `stationary and rod I4 turned relatively thereto.

This causes the end of the coil to .leavethe threading 22 and to enter the rhole 32.y As soon as the coil end is out of contact with the threadingg23 it will spring into close` engagement with the" flanks of the thread groove of the tapped hole 32,Y The pressure of the coil convoltions on rod I4 lbeing released owing` to the expansion of the coil, the tool canbe readily withdrawn.

Before this is qdone, the tang may be removed by turning the rod in the opposite direction in the manner described inl U. S. Patent .No. 2,210,061. Instead of passing the coil almost `entirely through the threading 23 before theifront end with the coil thereoniis inserted in the hole.

t 32, it is also possible to start the inserting operation when only a portion of the coil has been contracted. In the event, that, after `theinsertion, a short piece of the coil should still project from the tapped hole, such piece may be cut off in orderito make the coil `endfilush with the surface 34. l y

In Fig. 6, a modification of the braking means isshown. The member IIB which corresponds .to the memberllhas a." tapered rear end lwhose maximum diameter is smaller than the diameter of the main portion of the member IIB; the end`40 is `provided with longitudinal slots 4I and with a conical exterior threading 42. A nut 43 is screwed on that threading. By tight` ening the-nut more orless the friction between the end 40 and rod I4 canbe adequately adjusted. Nut 43 is shown as having a diameter of the same size as the member., IIB becausein `many cases where the tool may be used that space is so restricted thatradial projections must be avoided.

Fig. 7 illustrates' a modication of the part 2,2

` i and threading 23 which serves to contract a coil.

In the design according to Fig. .'7 the threading 223 in portion 222 of `member 2 Il is tapered from the rear towards` the iront face 224. The largest diameter of this threading corresponds to the outer diameter ofthe coiljprior to its contraction,` whereas the smallest` diameter of the 4threading 223 corresponds to the outer coil diameter in itsl contractedv state. Itwill be clear that a coil to, be contracted need not have a rst convolution II of reduced size as shown ,in Figs.

. "1 and2; that is to say, it may have the same diameter throughout itsl length if the threading 223 is provided which is capable of progressingly contracting the coil diameter from its maximum to its minimum diameter. In all other respects the modiiled tools are similar to the tool of Figs. 3 to 5. t

It will be apparent` to those lskilled in the art that many alterations and modicatiohs of the method and tool describedand illustrated by way of example are possible withinithe spirit of my invention which `shall be limited, therefore, only by the scope of the appended claims.

I claim: 1 t

1; A tool of-the character described, comprising a first member embodying means for gripping one end of a wire coll from the interior `oft the latter, and a second member embodying means for holding aportion of said wire coil from its outside, `both said members being co-axially arranged, and one of said members being axially shiftable and rotatable. in relationto'the other a member including' a bushing, a part provided one; whereby a coil portion between the grip and hold of the two members "respectively `can be `contracted if the one member` `is shifted an the two members to prevent a relative movement of the members owing to the tension of a contracted `coil portion between the grip and vhold of the two members respectively. t

, 3. A tool of the characterdescribed. comprising a rst rod-like member of i a diameter smaller than the inner diameter of a wire coil intended to be contracted by the tool, the front end of said first member being 'slotted so lasto receive in the slot a tang of the front end of the coil.

whensaid frontend of said rstrnember is passed'through said coil from `the rear end thereof, 'a'second member constituting a bushing in which said first member is axially shiftable and rotatable, said second-member embodying means for engaging and frictionally detaining a portion of said wire coil from the outside, and detaining `means in engagement with the two members to prevent a'relative movement of the members owing tothe tension ci a contracted coil *portion between the slotted end of said flrst member r and the detaining means of. said second member.

v4. A tool as claimed in `claim 31wherein the diameter of said first member is subtsantially equal to the desired inner diameter of the coil after its contraction.`

5. A tool of the character described comprising a mandrel with a slotted front end adapted to receive therein a `tang of the front end of a wire coil to be contracted, a member, including a bushing in which ysaid mandrel is axially shiftable and rotatable, said member also including apart provided with a tapped hole through which said front end of said mandrel can be projected. the thread diameter of said tapped hole correspondin'g to the diameter to which said coil is intended to be contracted, and detaining means in `engagement with said mandrel and said member to prevent a relative movement thereof owing to the tension of a contracted coil portion between t said mandrel and said part of said member.

6. Atooiias claimed in claim` -wherein said tapped hole is tapered from a maximum diameter corresponding substantially to the maximum diameter `of the coil prior to its contraction,

to a minimum diameter corresponding to that to which said coil is intended to be contracted.

7. A tool of the eharacter'described comprising with a `tapped hole co-axial with said bushing,

and a laterally recessed portion intermediate said bushing and said part. the threading of said tapped hole having a diameter corresponding to that to which a coil is intended to be con` erected, said intermediate portion being" so shaped as to receive the non-contracted coil between said bushing and saidV part, and a mani drel with a slotted front end` so as to receive,in said slot, a tang of the front end of said coil, 'said mandrel 'being rotatable in said bushing and axiaiiy shiftable therein .so as to be retmcinicie,v in the one direction, with its front end substantially intosafid bushing, and projectable, in the other direction, through a, coil placed in said recess, and with the coilon said end thmugh said tapped hole.

8. A tool 'as claimed in claim l'7 wherein said part provided with the tapped hole is provided bushing so as to exercise an adjustable clamping action onsaid mandrel.

y NE1L EVANS. 

